Probably the Relay.... or the LED, Try taking the relay out and cleaning the contacts as that is what powers the glowplugs.
Check the fuse @ f11 first tho, as that is what starts the biasing of the lamp. then check the fusible link on the battery.
Throw the Bentley out for wiring on the Westy, and use Chris's pages http://chris.chemidl.in/vw-wiring-diagram-pdf-1982-1983-1984/

Check the fuse @ f11 first tho, as that is what starts the biasing of the lamp. then check the fusible link on the battery.
Throw the Bentley out for wiring on the Westy, and use Chris's pages http://chris.chemidl.in/vw-wiring-diagram-pdf-1982-1983-1984/